Power Control in Wireless Communications Networks - From a Control Theory Perspective

Abstract

The global communications systems critically rely on control algorithms of various kinds. In wireless communications systems, power control algorithms play an important role for efficient resource utilization. This survey article discusses relevant aspects of power control with emphasis on practical issues, using an automatic control framework. Generally, power control of each connection is distributedly implemented as cascade control, with an inner loop to compensate for fast variations and an outer loop focusing on longer term statistics. These control loops are interrelated via complex connections, which affect important issues such as capacity, load and stability. Therefore, both local and global properties are important. The concepts and algorithms are illustrated by simple examples and simulations. Abstract: The global communications systems critically rely on control algorithms of various kinds. In wireless communications systems, power control algorithms play an important role for efficient resource utilization. This survey article discusses relevant aspects of power control with emphasis on practical issues, using an automatic control framework. Generally, power control of each connection is distributedly implemented as cascade control, with an inner loop to compensate for fast variations and an outer loop focusing on longer term statistics. These control loops are interrelated via complex connections, which affect important issues such as capacity, load and stability. Therefore, both local and global properties are important. The concepts and algorithms are illustrated by simple examples and simulations.

Impact of Cellular Phone Usage Duration on Power Control and Violation of EMC Regulations

“…An outer loop adjusts the reference SIR to assure that the quality of service is maintained. Outer loop control is typically based on bit error rates (BER) and block error rate (BLER) [1].…”

“…Power control has been the area subjected to intensive research [1]- [3]. Most of the research done, do focus on power control algorithms.…”

Modeling and Control of Ip Transport in Cellular Radio Links

“…This loop often has a sample frequency of 1500 Hz, and a one bit feedback that is subject to a delay of two samples, i.e., 1.3 ms. The inner loop is able to track the reference sinr ref within 2-3 dB, with a residual oscillation due to the delay and the severe quantization of the power control commands in the inner loop (Gunnarsson and Gustafsson, 2002). The period of this oscillation is typically less than 5 samples, i.e., 3.3 ms.…”

On localization with robust power control for safety critical wireless sensor networks

“…In Fig. 9(e) information feedback is used to implement equation (19) using β = 0.35 as suggested by [26]. The added flexibility associated with the use of information feedback is very apparent here.…”